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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 2 |
| 4 | 16 |
| 5 | 34 |
| 6 | 154 |
| 7 | 432 |
| 8 | 1618 |
| 9 | 5058 |
| 10 | 17664 |
| 11 | 57586 |
| 12 | 195866 |
| 13 | 648928 |
| 14 | 2185122 |
| 15 | 7284482 |
| 16 | 24435056 |
| 17 | 81651394 |
| 18 | 273490714 |
| 19 | 914714512 |
| 20 | 3062116338 |
| 21 | 10245066178 |
| 22 | 34289257824 |
| 23 | 114738331026 |
| 24 | 383986878106 |
| 25 | 1284957453248 |
| 26 | 4300144520002 |
[0,2,2,16,34,154,432,1618,5058,17664,57586,195866, 648928,2185122,7284482,24435056,81651394, 273490714,914714512,3062116338,10245066178, 34289257824,114738331026,383986878106, 1284957453248,4300144520002] |